Non-reducible dielectric ceramic material, making method, and multilayer ceramic capacitor

Abstract

In conjunction with the manufacture of a multilayer ceramic capacitor having nickel-containing internal electrodes involving a polishing step for exposing the end of the internal electrodes, a non-reducible dielectric ceramic material is prepared, for the purpose of preventing the polishing step from being prolonged, by furnishing a calcined material containing a compound oxide represented by the formula (I): [(Ca x Sr 1−x )O] m [(Ti y Zr 1−y )O 2 ] wherein 0≦x≦1, 0≦y≦0.10, and 0.75≦m≦1.04, as a main component, adding 0.001-10 mol % based on the main component of MgO or rare earth oxide and firing the mixture. The ceramic material contains predetermined amounts of SiO 2 and BaO and/or CaO, and MnO as auxiliary components.

What is claimed is:  
     
       1. A non-reducible dielectric ceramic material comprising 
       a compound oxide represented by the formula (I):  
       
         
           [(Ca x Sr 1−x )O] m [(Ti y Zr 1−y )O 2 ] 
         
       
        wherein 0≦x≦1, 0≦y≦0.10, and 0.75≦m≦1.04, as a main component,  
       0.5 to 15 mol % based on the main component of SiO 2  and BaO and/or CaO as an auxiliary component, these oxides being calculated as a compound oxide represented by the formula (II):  
       
         
           [(Ba z Ca 1−z )O] v SiO 2    
         
       
        wherein 0≦z≦1 and 0.5≦v≦4.0,  
       0.2 to 5 mol % based on the main component of MnO as an auxiliary component, and  
       0.001 to 10 mol % based on the main component of MgO as an additive component,  
       said material having been prepared by adding a starting raw material for the additive component to a calcined material containing the main component, followed by firing. 
     
     
       2. A non-reducible dielectric ceramic material according to claim  1  further comprising up to 10 mol % based on the main component of Al 2 O 3  as an auxiliary component. 
     
     
       3. A non-reducible dielectric ceramic material according to claim  1  which includes a silicon rich phase having a SiO 2  concentration which exceeds the average SiO 2  concentration of the entire ceramic material and is at least 10 mol %. 
     
     
       4. A non-reducible dielectric ceramic material according to claim  1  which is free of lithium. 
     
     
       5. A multilayer ceramic capacitor comprising a non-reducible dielectric ceramic material according to claim  1  as a dielectric material and internal electrodes containing at least nickel. 
     
     
       6. A non-reducible dielectric ceramic material comprising 
       a compound oxide represented by the formula (I):  
       
         
           [(Ca x Sr 1−x )O] m [(Ti y Zr 1−y )O 2 ] 
         
       
        wherein 0≦x≦1, 0≦y≦0.10, and 0.75≦m≦1.04, as a main component,  
       0.5 to 15 mol % based on the main component of SiO 2  as an auxiliary component,  
       0.2 to 5 mol % based on the main component of MnO as an auxiliary component, and  
       0.01 to 10 mol % based on the main component of at least one rare earth oxide selected from the group consisting of oxides of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, as an additive component,  
       said ceramic material being free of Al 2 O 3 .  
     
     
       7. A non-reducible dielectric ceramic material according to claim  6  wherein the auxiliary component includes CaO and/or BaO, which are contained along with SiO 2  in such proportions as to provide a compound oxide represented by the formula (II): 
       
         
           [(Ba z Ca 1−z )O] v SiO 2    
         
       
        wherein 0≦z≦1 and 0.5≦v≦4.0.  
     
     
       8. A non-reducible dielectric ceramic material according to claim  6  further comprising MgO. 
     
     
       9. A non-reducible dielectric ceramic material according to claim  6  which includes a silicon rich phase having a SiO 2  concentration which exceeds the average SiO 2  concentration of the entire ceramic material and is at least 10 mol %. 
     
     
       10. A non-reducible dielectric ceramic material according to claim  6  which is free of lithium. 
     
     
       11. A multilayer ceramic capacitor comprising a non-reducible dielectric ceramic material according to claim  6  as a dielectric material and internal electrodes containing at least nickel. 
     
     
       12. A non-reducible dielectric ceramic material comprising a compound oxide represented by the formula (I): 
       
         
           [(Ca x Sr 1−x )O] m [(Ti y Zr 1−y )O 2 ] 
         
       
        wherein 0≦x≦1, 0≦y≦0.10, and 0.75≦m≦1.04, as a main component,  
       0.5 to 15 mol % based on the main component of SiO 2  as an auxiliary component,  
       0.2 to 5 mol % based on the main component of MnO as an auxiliary component,  
       0.01 to 10 mol % based on the main component of at least one rare earth oxide selected from the group consisting of oxides of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, as an additive component, and  
       less than 0.1 mol % based on the main component of Al 2 O 3  as an auxiliary component.  
     
     
       13. A multilayer ceramic capacitor comprising a non-reducible dielectric ceramic material according to claim  12  as a dielectric material and internal electrodes containing at least nickel. 
     
     
       14. A non-reducible dielectric ceramic material comprising 
       a compound oxide represented by the formula (I):  
       
         
           [(Ca x Sr 1−x )O] m [(Ti y Zr 1−y )O 2 ] 
         
       
        wherein 0≦x≦1, 0≦y≦0.10, and 0.75≦m≦1.04, as a main component,  
       0.5 to 15 mol % based on the main component of SiO 2  as an auxiliary component,  
       0.2 to 5 mol % based on the main component of MnO as an auxiliary component, and  
       more than 1.5 to 10 mol % based on the main component of at least one rare earth oxide selected from the group consisting of oxides of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, as an additive component.  
     
     
       15. A non-reducible dielectric ceramic material according to claim  14  further comprising 0.1 to 10 mol % based on the main component of Al 2 O 3  as an auxiliary component. 
     
     
       16. A non-reducible dielectric ceramic material according to claim  14  wherein the auxiliary component includes CaO and/or BaO, which are contained along with SiO 2  in such proportions as to provide a compound oxide represented by the formula (II): 
       
         
           [(Ba z Ca 1−z )O] v SiO 2    
         
       
        wherein 0≦z≦1 and 0.5≦v≦4.0.  
     
     
       17. A non-reducible dielectric ceramic material according to claim  14  further comprising MgO. 
     
     
       18. A non-reducible dielectric ceramic material according to claim  14  which includes a silicon rich phase having a SiO 2  concentration which exceeds the average SiO 2  concentration of the entire ceramic material and is at least 10 mol %. 
     
     
       19. A non-reducible dielectric ceramic material according to claim  14  which is free of lithium. 
     
     
       20. A multilayer ceramic capacitor comprising a non-reducible dielectric ceramic material according to claim  14  as a dielectric material and internal electrodes containing at least nickel. 
     
     
       21. A method for preparing a non-reducible dielectric ceramic material comprising 
       a compound oxide represented by the formula (I):  
       
         
           [(Ca x Sr 1−x )O] m [(Ti y Zr 1−y )O 2 ] 
         
       
        wherein 0≦x≦1, 0≦y≦0.10, and 0.75≦m≦1.04, as a main component,  
       0.5 to 15 mol % based on the main component of SiO 2  and BaO and/or CaO as an auxiliary component, these oxides being calculated as a compound oxide represented by the formula (II):  
       
         
           [(Ba z Ca 1−z )O] v SiO 2    
         
       
        wherein 0≦z≦1 and 0.5≦v≦4.0,  
       0.2 to 5 mol % based on the main component of MnO as an auxiliary component, and  
       0.001 to 10 mol % based on the main component of MgO as an additive component,  
       said method comprising the steps of adding a starting raw material for the additive component to a calcined material containing the main component, followed by firing.